2006 Dodge Stratus Why does the front end shake so badly?

I have a 2006 Dodge Stratus. The front end shakes horribly bad once I hit about 55/60 mph and continues to get worse through 75 mph, after that it slows down. My husbands seems to think it may be the inner cv joints because we already replaced the wheel barings and it didn't do any good. If anything it got slightly worse. What could it be? Every mechanic I have taken it to tells me there is nothing wrong, but there again they won't take it for a drive either.